package com.lqk.nio.buffer;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * Scattering：将数据写入到Buffer时，可以采用Buffer数组，一次写入【分散】
 * Gathering：从Buffer读取数据时，可以采用Buffer数组，依次读取
 */
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws Exception {
        // 使用ServerSocketChannel和SocketChannel 网络
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7666);

        // 绑定端口到socket，并启动
        serverSocketChannel.socket().bind(inetSocketAddress);

        // 创建Buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0]=ByteBuffer.allocate(5);
        byteBuffers[1]=ByteBuffer.allocate(3);

        // 等客户端连接
        SocketChannel socketChannel = serverSocketChannel.accept();

        int messageLength=8;    // 假定从客户端接收8个字节
        // 循环读取
        while (true){
            int byteRead=0;
            while (byteRead<messageLength){
                long read = socketChannel.read(byteBuffers);
                byteRead += read;   // 累计读取的字节数
                System.out.println("byteRead="+byteRead);
                // 使用流打印，看看当前的这个Buffer的position和limit
                Arrays.asList(byteBuffers).stream()
                        .map(buffer->{
                            return "position="+buffer.position()+", limit="+buffer.limit();
                        }).forEach(System.out::println);
            }
            // 将所有的Buffer进行模式转换flip
            Arrays.asList(byteBuffers).forEach(buffer->{
                buffer.flip();
            });

            // 将数据读出显示到客户端
            long byteWrite=0;
            while (byteWrite<messageLength){
                long write = socketChannel.write(byteBuffers);
                byteWrite+=write;
            }

            // 将所有的Buffer进行clear
            Arrays.asList(byteBuffers).forEach(buffer->{
                buffer.clear();
            });

            System.out.println("byteRead="+byteRead+"byteWrite"+byteWrite+"messageLength"+messageLength);
        }
    }
}
